Thermal-control system of a video-recording doorbell and associated video-recording doorbells

ABSTRACT

This document describes a thermal-control system that is integrated into a video-recording doorbell. The thermal-control system includes a combination of heat spreaders and materials with high thermal conductivity. The thermal-control system may spread and dissipate energy from a thermal-loading condition effectuated upon the video-recording doorbell to concurrently maintain temperatures of multiple thermal zones on or within the video-recording doorbell at or below prescribed temperature thresholds.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 17/061,872, filed on Oct. 2, 2020, the disclosureof which is incorporated by reference herein in its entirety.

BACKGROUND

Video-recording doorbells are becoming a popular addition to homesecurity systems. A video-recording doorbell may be battery-powered andinclude multiple integrated-circuit (IC) devices, such as a passiveinfrared (PIR) sensor IC device that detects motion, an image sensor ICdevice that captures images, and a wireless-communication component thattransmits and receives data. The video-recording doorbell may alsoinclude a system-on-chip (SoC) IC device that executes amachine-learning algorithm.

The video-recording doorbell may, in some instances, include athermal-control system fabricated using a stamped sheet metal structurethat can dissipate heat from the SoC IC device during a thermal-loadingcondition, such as when the SoC IC device executes the machine-learningalgorithm for a short period of time and dissipates heat at a rate of upto 1½ Watts (W). In such an instance, the thermal-control system may becapable of dissipating the heat from the thermal-loading condition tomaintain a single prescribed temperature limit across the multiple ICdevices, effectively treating the video-recording doorbell as a singlethermal zone.

However, under certain thermal-loading conditions, such as when the SoCIC device executes the machine-learning algorithm for a lengthy periodof time and when the video-recording doorbell is exposed to solarradiation, the thermal loading on the video-recording doorbell canapproach or exceed 3 W. In such an instance, the thermal-control systemmay be inadequate to maintain the single prescribed temperature limitacross the multiple IC devices. The inability of the thermal-controlsystem to dissipate heat from the video-recording doorbell may result in(i) damage to one or more IC devices of the video-recording doorbelland/or (ii) a housing of the video-recording doorbell exceeding aprescribed ergonomic touch-temperature limit.

SUMMARY

This document describes a thermal-control system that is integrated intoa video-recording doorbell. The thermal-control system includes acombination of heat spreaders and materials with high thermalconductivity. The thermal-control system may spread and dissipate energyfrom a thermal-loading condition effectuated upon the video-recordingdoorbell to concurrently maintain temperatures of multiple thermal zoneson or within the video-recording doorbell at or below prescribedtemperature thresholds.

In some aspects, a thermal-control system for a video-recording doorbelland associated video-recording doorbells is described. Thethermal-control system includes a first thermal-control subsystemconfigured to transfer a first quantity of heat to a first housingcomponent and a second housing component of the video-recordingdoorbell. The first thermal-control subsystem includes a first thermalinterface material that is positioned between an SoC IC device and afirst hybrid graphite sheet that is fixed to a first heat spreader. Thefirst thermal-control subsystem also includes a second thermal interfacematerial that is positioned between a logic printed circuit board (PCB),to which the SoC IC device is attached, and a second heat spreader.

The thermal-control system also includes a second thermal-controlsubsystem configured to transfer a second quantity of heat to the firsthousing component and the second housing component of thevideo-recording doorbell. The second thermal-control subsystem includesa sensor PCB that has a separate ground plane for each of a passiveinfrared sensor IC device and an image sensor IC device. The secondthermal-control subsystem also includes a third thermal interfacematerial that is positioned between the sensor PCB and a third heatspreader.

In other aspects, a video-recording doorbell is described. Thevideo-recording doorbell includes an SoC IC device, a pressable button,a first housing component, and a second housing component. Thevideo-recording doorbell also includes a thermal-control system that isconfigured to concurrently maintain temperatures of multiple thermalzones of the video-recording doorbell during a thermal-loadingcondition. During the thermal-loading condition, the thermal-controlsystem may spread and dissipate heat to concurrently maintain (i) afirst temperature of a first thermal zone that includes thesystem-on-chip at or below a first prescribed temperature threshold,(ii) a second temperature of a second thermal zone that includes thepressable button at or below a second prescribed temperature threshold,and (iii) a third temperature of a third thermal zone that includes thefirst housing component and the second housing component at or below athird prescribed temperature threshold.

The details of one or more implementations are set forth in theaccompanying drawings and the following description. Other features andadvantages will be apparent from the description, the drawings, and theclaims. This summary is provided to introduce subject matter that isfurther described in the Detailed Description. Accordingly, a readershould not consider the summary to describe essential features nor limitthe scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more aspects of a thermal-control system for avideo-recording doorbell and associated video-recording doorbells aredescribed below. The use of the same reference numbers in differentinstances in the description and the figures indicate similar elements:

FIG. 1 illustrates an example operating environment in which aspects ofa thermal-control system for a video-recording doorbell can beimplemented.

FIG. 2 illustrates an exploded, isometric view of an examplevideo-recording doorbell in accordance with one or more aspects.

FIG. 3 illustrates a cross-section view and a magnified cross-sectionview of an example logic PCB thermal-control subsystem.

FIG. 4 illustrates an isometric exploded view of an example sensor PCBthermal-control subsystem.

FIG. 5 illustrates details of an example sensor PCB.

FIG. 6 illustrates example details of a hybrid graphite sheet that maybe used as part of a thermal-control system of a video-recordingdoorbell.

FIG. 7 illustrates example details of multiple thermal zones controlledby a thermal-control system of a video-recording doorbell.

DETAILED DESCRIPTION

This document describes a thermal-control system that is integrated intoa video-recording doorbell. The thermal-control system includes acombination of heat spreaders and materials having highthermal-conductivity. The thermal-control system may spread anddissipate energy from a thermal-loading condition effectuated upon thevideo-recording doorbell to concurrently maintain temperatures ofmultiple thermal zones within the video-recording doorbell at or belowprescribed temperature thresholds.

While features and concepts of the described thermal-control system canbe implemented in any number of different environments and devices,aspects are described in the context of the descriptions and examplesbelow.

Heat transfer, in general, is energy that is in transit due to atemperature difference. If one or more temperature differences existacross components of a system, such as the video-recording doorbell,heat (e.g., energy in Joules (J)) will transfer from higher-temperaturezones to lower-temperature zones to minimize the temperaturedifferences. There are several mechanisms for heat transfer across thecomponents of a system to minimize temperature differences, includingconvection, radiation, and conduction.

Convection, or heat transfer from a surface due to movement of moleculeswithin fluids such as gases and liquids, can be quantified by equation 1below:q _(conv) =hA(T _(s) −T _(∞))  (1)

For equation 1, q_(conv) represents a rate of heat transfer from asurface through convection (e.g., in J per second or Watts (W)), hrepresents a convection heat transfer coefficient (e.g., in Watts permeter squared (W/m²)), T_(s) represents a temperature of a surface(e.g., in Kelvin (K) or degrees Celsius (° C.)), and T_(∞) represents atemperature of a fluid (e.g., in K or ° C.) to which the surface isexposed. The term A represents the area of a surface (e.g., in m²).

Radiation, or heat transfer from a surface through electromagneticradiation, can be quantified by equation 2 below:q _(rad) =εAσ(T _(s) ⁴ −T _(surr) ⁴)  (2)

For equation 2, q_(rad) represents a rate of heat transfer throughradiation (e.g., in W), ε represents emissivity (dimensionless), σrepresents the Stefen-Boltzmann constant (e.g., σ=5.67×10⁻⁸ W/(m²·K⁴))T_(s) represents a temperature of a surface (e.g., in K or ° C.), andT_(surr) represents a temperature of surroundings of the surface (e.g.,K or ° C.). The term A represents an area of the surface (e.g., in m²).

Conduction, or heat transfer through a solid body through atomic andmolecular activity, can be quantified by equation 3 below:

$\begin{matrix}{q_{cond} = {{- k}A\frac{dT}{dx}}} & (3)\end{matrix}$

For equation 3, q_(cond) represents a rate of heat transfer in a solidmaterial through conduction (e.g., in W), k represents a thermalconductivity of the solid material (e.g., in W/(m·K)), and dT/dxrepresents a temperature gradient through the solid material (e.g., inK/m or ° C./m). The term A represents a cross-sectional area of thesolid material (e.g., in m²).

For a video-recording doorbell, heat transfer between components mayoccur using one or more of the heat transfer mechanisms described above.In general, and in accordance with equations (1) and (2), heat transfercan be varied by increasing or decreasing surface areas for convectionand/or radiation within the video-recording doorbell (e.g., increasingor decreasing surface areas of heat spreading mechanisms). Furthermore,and in accordance with equation (3), heat transfer can be varied bychoosing one or more interfacing materials having specific thermalconductivities. Through careful design of heat spreaders and the use ofinterfacing materials having the specific thermal conductivities, athermal-control system of the video-recording doorbell can concurrentlymaintain temperatures of different thermal zones at or below differentprescribed temperature thresholds during a thermal-loading condition.

FIG. 1 illustrates an example operating environment 100 having avideo-recording doorbell 102. In the example operating environment 100,a solar source (e.g., the sun) is radiating a solar heat load 104 (e.g.,q_(s)) onto exterior surfaces of the video-recording doorbell 102. Inthe example operating environment 100, at least one electronic device(e.g., integrated circuitry) is generating an internal heat load 106(e.g., q_(i)) within the video-recording doorbell 102. The exampleoperating environment 100 may include a 1000 Watts per square meter(W/m²) solar heat load 104, and a 3 W internal heat load 106.

FIG. 1 also illustrates elements of a thermal-control system 108 thatmay control multiple thermal zones of the video-recording doorbell 102.In general, the thermal-control system 108 may spread, store, anddissipate energy from a thermal-loading condition (e.g., the solar heatload 104 in combination with the internal heat load 106) effectuatedupon the video-recording doorbell 102 to concurrently maintaintemperatures of multiple thermal zones within the video-recordingdoorbell 102.

In instances where the multiple thermal zones of the video-recordingdoorbell 102 have different respective temperature thresholds, theability of the thermal-control system 108 to concurrently maintaintemperatures of the multiple thermal zones at or below the differentprescribed temperature thresholds is advantageous over otherthermal-control systems for other video-recording doorbells that lacksuch capabilities. For example, in addition to ensuring that thermalperformance of the video-recording doorbell 102 meets an ergonomicrequirement (e.g., touch temperature), the ability of thethermal-control system 108 to maintain the multiple thermal zones at orbelow different and respective prescribed temperature thresholds mayextend the life of one or more IC devices included in thevideo-recording doorbell 102.

The thermal-control system 108 includes a logic PCB thermal-controlsubsystem 110 and a sensor PCB thermal-control subsystem 112. Under thethermal-loading condition, the dissipated heat 114 (e.g., q_(d)), asspread throughout the video-recording doorbell 102 using the logic PCBthermal-control subsystem 110 and the sensor PCB thermal-controlsubsystem 112, may be equivalent to a sum of the solar heat load 104 andthe internal heat load 106 (e.g., q_(d)=q_(i)+q_(s)).

FIG. 2 illustrates an exploded, isometric view 200 of thevideo-recording doorbell 102 of FIG. 1 . As illustrated in FIG. 2 , thevideo-recording doorbell 102 includes an SoC IC device 202 that ismounted to a logic PCB 204. In the operating environment 100, the SoC ICdevice 202 may execute machine-learning algorithms for an extendedduration (e.g., 10 minutes or more), which generates portions of aninternal heat load (e.g., the internal heat load 106 as illustrated inFIG. 1 ).

The video-recording doorbell also includes a PIR sensor IC device 206and an image sensor IC device 208. The PIR sensor IC device 206 and theimage sensor IC device 208 are mounted to a sensor PCB 210. The PIRsensor IC device 206 may sense motion external to the video-recordingdoorbell 102, while the image sensor IC device 208 may capture imageswithin a field of view of the video-recording doorbell 102.

The video-recording doorbell includes a pressable button 212, a firsthousing component 214, and a second housing component 216. The firsthousing component 214 and the second housing component 216 may, ingeneral, be complementary in size and shape. For example, asillustrated, the first housing component 214 is elongated along a firstaxis and includes a first set of opposing ends that have a generallyradial curvature. The second housing component 216 is elongated along asecond axis that is generally parallel to the first axis. Furthermore,the second housing component 216, as illustrated, includes a second setof opposing ends that substantially match the generally radial curvatureof the first set of opposing ends of the first housing component 214.The first housing component 214 and the second housing component 216 mayinclude recesses and/or channels for alignment and coupling.

Continuing with FIG. 2 , the video-recording doorbell 102 furtherincludes a battery 218. The battery 218 may power the video-recordingdoorbell 102. Multiple thermal-control subsystems (e.g., the logic PCBthermal control subsystem 110 and the sensor PCB thermal-controlsubsystem 122) may be included in the video-recording doorbell 102 toconcurrently control multiple thermal zones within the video-recordingdoorbell 102. The thermal-control subsystems may concurrently spread theheat (e.g., solar heat load 104, internal heat load 106 of FIG. 1 )throughout the video-recording doorbell 102 using heat transfer modesthat include conduction, convection, and/or radiation. The heat maysubsequently be dissipated through exterior surfaces of thevideo-recording doorbell 102 (e.g., surfaces of the pressable button212, the first housing component 214, the second housing component 216).

The logic PCB thermal-control subsystem 110 may include elementsdirected to conducting and spreading heat from the SoC IC device 202.For instance, the logic PCB thermal-control subsystem 110 may include afirst thermal interface material (TIM) 220 (e.g., an SoC IC devicetopside TIM) and a first hybrid graphite sheet 222 (not visible in FIG.2 ) fixed to a first heat spreader 224 (e.g., an electromagneticinterference (EMI) heat spreader) that doubles as an electromagneticinterference (EMI) shield. The first heat spreader 224 may have asubstantially rectangular shape that substantially fits within anoutline of the logic PCB 204. For example, the first heat spreader 224may have a width that is approximately 80% to 100% of a width of thelogic PCB 204 and a length that is approximately 40% to 60% of a lengthof the logic PCB 204.

The logic PCB thermal-control subsystem 110 may also include a secondTIM 226 (e.g., an SoC IC device backside TIM), a second heat spreader228 (e.g., a logic PCB heat spreader), and a second hybrid graphitesheet 230 that is fixed to the second heat spreader 228. The second heatspreader 228 may have a substantially rectangular shape thatsubstantially fits within an outline of the logic PCB 204. For example,the second heat spreader 228 may have a width that is approximately 80%to 100% of a width of the logic PCB 204 and a length that isapproximately 60% to 90% of a length of the logic PCB 204.

As illustrated in FIG. 2 , the first TIM 220 is in thermal contact with,and positioned between, the SoC IC device 202 and the first hybridgraphite sheet 222. Also, as illustrated in FIG. 2 , the second TIM 226is in thermal contact with, and positioned between, the second heatspreader 228 and a second surface of a logic PCB 204 that is opposite afirst surface of the logic PCB 204 to which the SoC IC device 202 ismounted. In some instances, the logic PCB 204 may include holes and ornotches that may be used to align the logic PCB 204 to the second heatspreader 228 (e.g., the second heat spreader 228 may have flanges and/oralignment pins).

Elements of the logic PCB thermal-control subsystem 110 may include acombination of materials and/or material stacks. For example, the firstheat spreader 224 may include a copper material while the second heatspreader 228 may include an aluminum alloy material. The first hybridgraphite sheet 222 and the second hybrid graphite sheet 230 may eachinclude a layering of graphite, pressure-sensitive adhesive (PSA), andpolyethylene terephthalate (PET) films. The first TIM 220 and the secondTIM 226 include a gel material that includes a silicone-rubber materialinjected with nanoparticles (e.g., aluminum nanoparticles,beryllium-nitride nanoparticles). Alternatively, the first TIM 220 andthe second TIM 226 might include a thermal grease material or athermally-conductive foam material.

The sensor PCB thermal-control subsystem 112 may include elementsdirected to conducting and spreading heat away from the PIR sensor ICdevice 206 and the image sensor IC device 208. The sensor PCBthermal-control subsystem 112 may conduct and spread heat originatingfrom a solar source and/or the SoC IC device 202 (e.g., the solar heatload 104 and/or the internal heat load 106 of FIG. 1 ). The sensor PCB210 may be enhanced, including separate ground planes for the PIR sensorIC device 206 and the image sensor IC device 208 to enable thermalisolation between the PIR sensor IC device 206 and the image sensor ICdevice 208.

Elements of the sensor PCB thermal-control subsystem 112 also include athird TIM 232 (e.g., an image sensor IC device backside TIM) and a thirdheat spreader 234 (e.g., an image sensor IC device heat spreader). Asillustrated in FIG. 1 , the third TIM 232 is in thermal contact with,and positioned between, the third heat spreader 234 and a second surfaceof the sensor PCB 210 that is opposite to the first surface upon whichthe PIR sensor IC device 206 and image sensor IC device 208 are mounted.

The sensor PCB thermal-control subsystem 112 may include differentcombinations of materials. The third TIM 232 may be made up of a gelmaterial with high thermal-conductivity (e.g., W/(m·K)) that includes asilicone-rubber material injected with nanoparticles such as aluminum,beryllium-nitride, and so on.

Generally, depending upon varying thermal-loading conditions (e.g.,thermal-loading conditions that vary with changes to ambienttemperatures, solar intensity, or operative power of the SoC IC device202), the logic PCB thermal-control subsystem 110 and the sensor PCBthermal-control subsystem 112 may each transfer a different quantity ofheat. For example, for a given thermal-loading condition, the logic PCBthermal-control subsystem 110 may transfer (e.g., through convection,radiation, and/or conduction) a first quantity of heat to the firsthousing component 214 and the second housing component 216. For the samegiven thermal-loading condition, the sensor PCB thermal-controlsubsystem 112 may transfer (e.g., through convection, radiation, and/orconduction) a second quantity of heat to the first housing component 214and the second housing component 216.

When coupled, the first housing component 214 and the second housingcomponent 216 combine to form a housing that has an elongated shape. Ingeneral, the pressable button 212 and the image sensor device 132 arepositioned at opposite ends of the elongated shape. The thermal-controlsystem 108 may be located within the housing, with at least someportions of the thermal-control system 108 located between the pressablebutton 212 and the image sensor device 132.

The logic PCB thermal-control subsystem 110 and the sensor PCBthermal-control subsystem 112 are passive. As designed, neither thelogic PCB thermal-control subsystem 110 nor the sensor PCBthermal-control subsystem 112 require active or powered fans or pumps toconcurrently maintain temperatures of multiple thermal zones (e.g.,multiple thermal zones of the video-recording doorbell 102 of FIG. 1 )at or below prescribed temperature thresholds.

FIG. 3 illustrates a cross-section view 300 and a magnifiedcross-section view 302 of the logic PCB thermal-control subsystem 110.The magnified cross-section view 302 illustrates details of the logicPCB thermal-control subsystem 110. Beginning at the far left of themagnified cross-section view 302 is the first housing component 214(e.g., the top-housing component) and the first heat spreader 224. Afirst air gap 304 separates the first housing component 214 and thefirst heat spreader 224. A width of the first air gap 304 may be variedto change thermal heat transfer characteristics between the first heatspreader 224 and the first housing component 214 (e.g., increasing thewidth of the first air gap 304 will decrease a thermal conductivity anddecrease rates of heat exchange through convection and/or radiationbetween the first heat spreader 224 and the first housing component214).

Additionally, the first hybrid graphite sheet 222 distributes heatacross the first heat spreader 224 (e.g., the EMI shield heat spreader).The first heat spreader 224 may spread a quantity of heat originatingacross the first heat spreader 224, effectuating an increase inefficiency and effectiveness with which the first heat spreader 224exchanges heat with the first housing component 214.

The magnified cross-section view 302 also illustrates the first TIM 220(e.g., the SoC IC device topside TIM) positioned between the firsthybrid graphite sheet 222 and the SoC IC device 202. The first TIM 220may serve as a conduction path between the SoC IC device 202 and thefirst hybrid graphite sheet 222. By reducing air gaps and/or bond linegaps between the SoC IC device 202 and the first hybrid graphite sheet222, the first TIM 220 improves thermal conductivity and increases anefficiency and effectiveness with which the SoC IC device 202 exchangesheat with the first hybrid graphite sheet 222.

The magnified cross-section view 302 also illustrates the logic PCB 204to which the SoC IC device 202 is mounted. The SoC IC device 202 may bemounted to the first surface of the logic PCB 204 through surface-mounttechniques (e.g., soldering external, electrical contacts of the SoC ICdevice 202 to electrically conductive pads of the logic PCB 204). Thelogic PCB 204 may be a multi-layer PCB, with layers of aluminum orcopper traces that communicate signals between the SoC IC device 202 toother components of the video-recording doorbell 102. In some instances,a thickness of the logic PCB 204 can be in a range that is betweenapproximately 0.40 millimeters (mm) and 0.50 mm.

The magnified cross-section view 302 also includes the second TIM 226(e.g., the SoC IC device backside TIM) that is located between thesecond surface of the logic PCB 204 and the second heat spreader 228(e.g., the logic PCB heat spreader). In some instances, the second heatspreader 228 may be stamped from a metal such as an aluminum alloy, acopper material, and so on. The second heat spreader 228 may have athickness that is in a range between approximately 0.40 mm and 0.50 mm.The magnified cross-section view 302 also illustrates the second hybridgraphite sheet 230 that is adhered to the second heat spreader 228.

Continuing in FIG. 3 , the magnified cross-section view 302 illustratesa second air gap 306 that separates the second hybrid graphite sheet 230from the battery 218. A width of the second air gap 306 may be varied tochange thermal heat transfer characteristics between second hybridgraphite sheet 230 and the battery 218 (e.g., increasing the width ofthe second air gap 306 may reduce thermal conductivity and decreaserates of heat exchange through convection and/or radiation between thesecond hybrid graphite sheet 230 and the battery 218). In someinstances, the second air gap 306 may impede heat of the internal heatload 106 (e.g., q_(i) of FIG. 1 ) from transferring into the battery218.

FIG. 4 illustrates an isometric exploded view 400 of the sensor PCBthermal-control subsystem 112 of FIG. 1 . The isometric exploded view400 illustrates the sensor PCB 210 having a surface 402 to which the PIRsensor IC device 206 and the image sensor IC device 208 are mounted. Theisometric exploded view 400 also illustrates the third TIM 232positioned between the third heat spreader 234 and another surface 404of the sensor PCB 210 that is opposite to the surface upon which the PIRsensor IC device 206 and image sensor IC device 208 are mounted. In anassembled state, the third TIM 232 is in thermal contact with the sensorPCB 210 and the third heat spreader 234. The third heat spreader 234 mayinclude a material such as a copper material or an aluminum alloymaterial. The third heat spreader 234 may also have a shape thatconforms substantially to that of the sensor PCB 210.

In some instances, the third heat spreader 234 may include one or moreflange(s) 406 and/or one or more alignment pin(s) 408. The flange(s) 406and the alignment pin(s) 408, in some instances, may position the thirdheat spreader 234 relative to the sensor PCB 210 such that thermalcontact between features of the sensor PCB 210 and the third heatspreader 234 is optimized (e.g., for thermal conduction). The flange(s)406 and the alignment pin(s) 408 may further contribute to the sensorPCB thermal-control subsystem 112 as thermal conduction paths betweenthe sensor PCB 210 and the third heat spreader 234. In some instances,the flange(s) 406 may also perform as mechanical standoffs that areconducive to a desired thickness and/or compression of the third TIM232.

In some instances, the third TIM 232 may include a thermal pad. Examplesof the thermal pad include a preformed solid material that is siliconeor paraffin wax-based. The third TIM 232 may provide a conductive pathfor heat generated by the PIR sensor IC device 206 and the image sensorIC device 208 to the third heat spreader 234, which may transfer thegenerated heat through convection and/or radiation to other elements(e.g., the first housing component 214 and/or to the second housingcomponent 216 illustrated in FIG. 1 ). In some instances, a hybridgraphite sheet (not illustrated in FIG. 3 ) may also adhere to one ormore surfaces of the third heat spreader 234.

In general, the sensor PCB thermal-control subsystem 112 may contributeto maintaining multiple thermal zones of a video-recording doorbell(e.g., the video-recording doorbell 102 of FIG. 1 ) at or below aprescribed temperature threshold. Depending on differences in thermalpotentials (e.g., temperatures) in or on a video-recording doorbell,features of the sensor PCB thermal-control subsystem 112 (e.g., thesensor PCB 210, the third TIM 232, and the third heat spreader 234) mayperform in unison to transfer heat away from the PIR sensor IC device128 and/or the image sensor device 132 to housing components of thevideo-recording doorbell.

FIG. 5 illustrates details 500 of the sensor PCB 210 of FIG. 2 . Asillustrated, the sensor PCB 210 includes several features directed toimproving heat transfer characteristics. The sensor PCB 210 includes afirst ground plane 502 that is thermally isolated from a second groundplane 504 (e.g., metal layering features that form the first groundplane 502 and the second ground plane 504 are independent of one anotherwith no shared metallic paths to conduct electrical and/or thermalenergy). As illustrated, the sensor PCB 210 includes a slot 506 thatthermally separates the first ground plane 502 from the second groundplane 504.

The first ground plane 502 and the second ground plane 504 may be groundplanes for different sensors. For example, the first ground plane 502may be a ground plane for a PIR sensor IC device (e.g., the PIR sensorIC device 206 of FIGS. 2 and 4 ), and the second ground plane 504 may bea ground plane for an image sensor IC device (e.g., the image sensor ICdevice 208 of FIGS. 2 and 4 ). Due to the thermal isolation of the firstground plane 502 from the second ground plane 504, transfer of heatbetween sensors is prevented. In some instances, the first ground plane502 and the second ground plane 504 may be formed from a material thathas a thermal conductivity and/or a thermal capacitance (e.g., a coppermaterial). In some instances, the sensor PCB 210 may include one or morehole(s) 508 that may be used to align the sensor PCB 210 to a heatspreader.

FIG. 6 illustrates details 600 of an example hybrid graphite sheet thatmay be used as part of a thermal-control system of a video-recordingdoorbell. The hybrid graphic sheet may be the second hybrid graphitesheet 230 of FIGS. 2 and 3 , used in the video-recording doorbell ofFIG. 1 .

The second hybrid graphite sheet 230 may include a layering 602 ofgraphite, PSA, and PET films. As illustrated, the layering 602 includestwo layers of graphite film 604, two layers of PSA film 606, a layer ofPET protective film 608, and a layer of PET release film 610.

Although FIG. 6 illustrates the layering 602 included as part of thesecond hybrid graphite sheet 230, the layering 602 (or variationsthereof) may be included in other hybrid graphite sheets (e.g., thefirst hybrid graphite sheet 222 of FIG. 1 , not illustrated).

FIG. 7 illustrates example details 700 of multiple thermal zonescontrolled by the thermal-control system 108 of the video-recordingdoorbell 102. Included in FIG. 7 is an example schematic (also referredto as a thermal circuit diagram) depicting sources of thermal loadingand paths for heat transfer within the video-recording doorbell 102. Ingeneral, the thermal-control system 108 may spread, store, and dissipateenergy from a thermal-loading condition (e.g., the solar heat load 104in combination with the internal heat load 106) effectuated upon thevideo-recording doorbell 102 to concurrently maintain temperatures ofthe multiple thermal zones within the video-recording doorbell 102.

The multiple thermal zones include a first thermal zone 702, includingthe SoC IC device 202. The first thermal zone 702 may have a firstprescribed temperature threshold corresponding to a maximum allowablejunction temperature of a diode within the SoC IC device 202 under athermal-loading condition (e.g., when both the solar heat load 104 andthe internal heat load 106 are exuding heat upon the video-recordingdoorbell 102). As an example, the first prescribed temperature thresholdmay be approximately 100 degrees Celsius (° C.). In such an instance,the thermal-control system 108 may spread and dissipate heat throughoutthe video-recording doorbell 102 to maintain the first thermal zone 702at or below the first prescribed temperature threshold (e.g., thejunction temperature of the diode within the SoC IC device 202 may bemaintained at or below 100° C. under the thermal-loading condition).

A second thermal zone 704 that includes the pressable button 212 is alsopart of the multiple thermal zones. The pressable button 212 may be abutton that a user pushes to activate or ring the doorbell. The secondthermal zone 704 may have a second prescribed temperature thresholdcorresponding to a maximum allowable ergonomic touch temperature of thepressable button 212. As an example, the second prescribed temperaturethreshold may be approximately 77° C. In such an instance, thethermal-control system 108 may concurrently spread and dissipate heatthroughout the video-recording doorbell 102 to maintain the secondthermal zone 704 at or below the second prescribed temperature threshold(e.g., the maximum allowable ergonomic touch temperature of thepressable button 212 may be maintained at or below 77° C. under thethermal-loading condition).

A third thermal zone 706 that includes the first housing component 214and the second housing component 216 is also part of the multiplethermal zones. The third thermal zone 706 may have a third prescribedtemperature threshold corresponding to a maximum allowable ergonomictouch temperature of the first housing component 214 and/or the secondhousing component 216. As an example, the third prescribed temperaturethreshold may be approximately 85° C. In such an instance, thethermal-control system 108 may concurrently spread and dissipate heatthroughout the video-recording doorbell 102 to maintain the thirdthermal zone 706 at or below the third prescribed temperature threshold(e.g., the maximum allowable ergonomic touch temperature of the firsthousing component 214 and/or the second housing component 216 may bemaintained at or below 85° C. under the thermal-loading condition).

The multiple thermal zones also include a fourth thermal zone 708 thatincludes the PIR sensor IC device 128. The fourth thermal zone 708 mayhave a fourth prescribed temperature threshold corresponding to amaximum allowable junction temperature of a diode within the PIR sensorIC device 128. As an example, the second prescribed temperaturethreshold may be approximately 80° C. In such an instance, thethermal-control system 108 may concurrently spread and dissipate heatthroughout the video-recording doorbell 102 to maintain the fourththermal zone 708 at or below the fourth prescribed temperature threshold(e.g., the junction temperature of the diode within the PIR sensor ICdevice 128 may be maintained at or below 80° C. under thethermal-loading condition).

A fifth thermal zone 710 that includes the image sensor IC device 208 isalso included in the multiple thermal zones. The fifth thermal zone 710may have a fifth prescribed temperature threshold corresponding to amaximum allowable junction temperature of a diode within the imagesensor IC device 208. As an example, the fifth prescribed temperaturethreshold may be approximately 85° C. In such an instance, thethermal-control system 108 may concurrently spread and dissipate heatthroughout the video-recording doorbell 102 to maintain the fifththermal zone 710 at or below the fifth prescribed temperature threshold(e.g., the junction temperature of the diode within the image sensor ICdevice 208 may be maintained at or below 85° C. under thethermal-loading condition).

The multiple thermal zones also include a sixth thermal zone 712 thatincludes the battery 218, which may power the video-recording doorbell102. The sixth thermal zone 712 may have a sixth prescribed temperaturethreshold corresponding to a maximum allowable surface temperature ofthe battery 218. As an example, the sixth prescribed temperaturethreshold may be approximately 80° C. In such an instance, thethermal-control system 108 may concurrently spread and dissipate heatthroughout the video-recording doorbell 102 to maintain the sixththermal zone 712 at or below the sixth prescribed temperature threshold(e.g., the surface temperature of the battery 218 may be maintained ator below 80° C. under the thermal-loading condition).

The thermal-control system 108 may include a combination ofthermal-control subsystems (e.g., the logic PCB thermal-controlsubsystem 110 and the sensor PCB thermal-control subsystem 112)operating in parallel to concurrently spread heat throughout thevideo-recording doorbell 102. The thermal-control subsystems mayconcurrently spread the heat (e.g., solar heat load 104, internal heatload 106) throughout the video-recording doorbell 102 using heattransfer modes that include conduction, convection, and/or radiation.The heat may subsequently be dissipated through exterior surfaces of thevideo-recording doorbell 102 (e.g., surfaces of the pressable button212, the first housing component 214, the second housing component 216)to concurrently maintain temperatures of the multiple thermal zones(702, 704, 706, 708, 710, 712) at or below prescribed temperaturethresholds. Furthermore, and in general, the thermal-control system 108is a passive thermal-control system.

Although techniques using and apparatuses for a thermal-control systemof a video-recording doorbell are described, it is to be understood thatthe subject of the appended claims is not necessarily limited to thespecific features or methods described. Rather, the specific featuresand methods are disclosed as example ways in which a thermal-controlsystem of a video-recording doorbell can be implemented.

What is claimed is:
 1. A thermal-control system for a video-recordingdoorbell, the thermal-control system comprising: a first thermal-controlsubsystem, the first thermal-control subsystem configured to transfer afirst quantity of heat to a housing of the video-recording doorbell, thefirst thermal-control subsystem including: a first thermal interfacematerial, the first thermal interface material positioned between afirst hybrid graphite sheet and a system-on-chip integrated circuitdevice mounted to a first surface of a logic printed circuit board, thefirst hybrid graphite sheet fixed to a first heat spreader, the firstheat spreader is separated from the housing by a first air gap; and asecond thermal interface material, the second thermal interface materialpositioned between a second heat spreader and a second surface of thelogic printed circuit board that is opposite the first surface; and asecond thermal-control subsystem, the second thermal-control subsystemconfigured to transfer a second quantity of heat to the housing of thevideo-recording doorbell, the second thermal-control subsystem includinga third thermal interface material, the third thermal interface materialpositioned between a third heat spreader and a first surface of a sensorprinted circuit board having a second surface that is opposite the firstsurface and that has first and second ground planes that are configuredfor different sensors from one another.
 2. The thermal-control system ofclaim 1, wherein the housing includes: a first housing component that iselongated along a first axis and includes a first set of opposing ends,the first set of opposing ends having a generally radial curvature; anda second housing component that is elongated along a second axis that isgenerally parallel to the first axis, the second housing componentcomplementary to the first housing component and having a second set ofopposing ends substantially matching the generally radial curvature ofthe first set of opposing ends of the first housing component.
 3. Thethermal-control system of claim 1, wherein the first thermal interfacematerial includes a gel material that includes a silicone-rubbermaterial injected with nanoparticles.
 4. The thermal-control system ofclaim 1, wherein the first heat spreader is part of an electromagneticinterference shield.
 5. The thermal-control system of claim 4, whereinthe first heat spreader includes a copper material.
 6. Thethermal-control system of claim 1, wherein the first hybrid graphitesheet includes a layering of graphite, pressure-sensitive adhesive, andpolyethylene terephthalate films.
 7. The thermal-control system of claim1, wherein the second thermal interface material includes a gelmaterial.
 8. The thermal-control system of claim 7, wherein the gelmaterial includes a silicone-rubber material injected withnanoparticles.
 9. The thermal-control system of claim 1, wherein: thesecond thermal-control subsystem includes the sensor printed circuitboard; and the sensor printed circuit board includes a slot thatthermally separates the first ground plane from the second ground plane.10. The thermal-control system of claim 9, wherein: the first groundplane on the second surface of the sensor printed circuit board isconfigured for a passive infrared sensor integrated circuit device; andthe second ground plane on the second surface of the sensor printedcircuit board is configured for an image sensor integrated circuitdevice.
 11. The thermal-control system of claim 1, wherein the thirdthermal interface material is a thermal pad.
 12. The thermal-controlsystem of claim 11, wherein the thermal pad includes a preformed solidmaterial that is silicone-based or paraffin wax-based.
 13. Thethermal-control system of claim 1, wherein the second heat spreaderincludes an aluminum material and has a thickness within a range ofapproximately 0.40 millimeters to approximately 0.50 millimeters. 14.The thermal-control system of claim 1, wherein: the second heat spreaderis fixed to a second hybrid graphite sheet; and the second hybridgraphite sheet is separated from a battery of the video-recordingdoorbell by a second air gap.
 15. The thermal-control system of claim14, wherein the second hybrid graphite sheet includes a layering ofgraphite, pressure-sensitive adhesive, and polyethylene terephthalatefilms.
 16. A video-recording doorbell comprising: a system-on-chipintegrated circuit device; a pressable button; an image sensorintegrated circuit device; a housing; and a thermal-control systemconfigured to concurrently maintain temperatures throughout thevideo-recording doorbell during a thermal-loading condition, thethermal-control system configured to concurrently maintain: a firsttemperature of a first thermal zone at or below a first prescribedtemperature threshold, the first thermal zone including thesystem-on-chip integrated circuit device; a second temperature of asecond thermal zone at or below a second prescribed temperaturethreshold, the second thermal zone including the pressable button; and athird temperature of a third thermal zone at or below a third prescribedtemperature threshold, the third thermal zone including the image sensorintegrated circuit device.
 17. The video-recording doorbell of claim 16,wherein maintaining the first temperature of the first thermal zone ator below the first prescribed temperature threshold relies, in part,upon a first thermal-control subsystem, the first thermal-controlsubsystem configured to transfer a first quantity of heat to thehousing, the first thermal-control subsystem including: a first thermalinterface material, the first thermal interface material positionedbetween a surface of the system-on-chip integrated circuit device and afirst hybrid graphite sheet, the first hybrid graphite sheet adhered toa first heat spreader; and a second thermal interface material, thesecond thermal interface material positioned between a surface of alogic printed circuit board to which the system-on-chip integratedcircuit device is attached and a second heat spreader, the second heatspreader fixed to a second hybrid graphite sheet.
 18. Thevideo-recording doorbell of claim 17, wherein: the video-recordingdoorbell further comprises: a passive infrared sensor integrated circuitdevice; and a battery; and the thermal-control system is furtherconfigured to concurrently maintain: a fourth temperature of a fourththermal zone at or below a fourth prescribed temperature threshold, thefourth thermal zone including the passive infrared sensor integratedcircuit device; a fifth temperature of a fifth thermal zone at or belowa fifth prescribed temperature threshold, the fifth thermal zoneincluding the housing; and a sixth temperature of a sixth thermal zoneat or below a sixth prescribed temperature threshold, the sixth thermalzone including the battery.
 19. The video-recording doorbell of claim18, wherein: the maintaining of the fourth temperature of the fourththermal zone at or below the fourth prescribed temperature threshold andthe maintaining of the fifth temperature of the fifth thermal zone at orbelow the fifth prescribed temperature threshold relies, in part, upon asecond thermal-control subsystem configured to transfer a secondquantity of heat to the housing and away from the image sensorintegrated circuit device; and the second thermal-control subsystemincludes a third thermal interface material, the third thermal interfacematerial positioned between a third heat spreader and a first surface ofa sensor printed circuit board.
 20. The video-recording doorbell ofclaim 19, wherein the sensor printed circuit board includes a separateground plane for each of the passive infrared sensor integrated circuitdevice and the image sensor integrated circuit device mounted to asecond surface of the sensor printed circuit board that is opposite thefirst surface.